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SHOULDER BLADE AND LOCOMOTION

37

the spine, the prescapular lamina, is most extensively developed in
such animals as per-
form complex move-
ments with the fore-
limbs. The Sea lion
and the Great Anteater
are cited by Professor
G-. B. Howes as ex-
amples of this pre-
ponderance of the an-
terior portion of the
scapula over that which
lies behind the spine.
The general shape of FlG-27.-

af

Right scapula of Dolphin (Tursiops

a, Aeromion ; «/", prescapular fossa ; c, cora-

coid ;   gcf glenoid cavity ; pf, postscapular fossa*

(From Flower's Osteology.)

the scapula varies con-
siderably among the
different orders of mammals ; but it always presents the characters

mentioned, which are nowhere seen
among the Sauropsida except among
certain Anomodonts, which will be
duly referred to (see p. 90). The
most conspicuous divergences from
the normal are to be found in the
Cetacea and the Monotremata. In
the former the acromion is approxi-
mated so nearly to the anterior
border of the blade-bone that the
prescapular fossa is reduced to a
very small area ; and in Platanista
the acromion actually coincides
rt0 ., , . -..,,.,,** with the anterior border, so that

FIG.  28.—Side  view  of  right half  of                                                *

shoulder girdle of a young Echidna   that lOSSa actually disappears.      ill

(Mchidna hystrix)    xf    a, Aero-  tl     whales, too, the scapula is as

imon ;    c,   coracoid;    cbt   coracoid                            }         *                  *

border ; d, clavicle ; ess, coraco- a rule very broad, especially above;
scapular .suture ; ec, epworaooid^ ^ jlag freqUently a fan-like coiitoux.
cavity; ic, interciavicie; pf, post- In the Monotremata the acromion

sC>i?ie*• «» ^i^rascapnitir eSp^ai/- als° coincides with the ^anterior
.s%?/, s\ii>scapuiar fossa. (From border of the scapula; but the
Flower's Oitotoffyj                      sameness of appearance which it

,-.                       X/*i-1*J?4-       \4-         4*1-.     /1^J--~___________** -        *

tllllS    l»rPROTlt.«    flTl     tllT«    +^.*i-ii-r.^A    <-^    4-W-